Cooler Sizing

Swamp Cooler Sizing

When choosing an indoor Swamp Cooler sizing is very important, you want to choose the right swamp cooler for the size of the space you want to cool. Evaporative Cooler sizing is measured in Cubic Feet per Minute or CFM, most quality indoor Swamp Coolers will have a CFM rating. The CFM rating is how much air the cooler will circulate in a minute. When shopping for a cooler you will see they say 5300 CFM or 2100 CFM, this means they put out 5300 Cubic Feet per Minute or 2100 etc. Basically CFM is based on the size of the fan in the cooler combined with the motor that powers it. This is what you will want to know when calculating what cooler size you need, and there are many sizes available. Here we will show you how to calculate what evaporative cooler sizing you need to make the right decision and get the best cooler to meet your cooling needs.

The formula for calculating evaporative cooler sizing for indoor use is as follows:

Take the square footage/feet of the space that needs cooling x the ceiling height (in feet), take this number and divide it by 2 or cut it in half and that’s how much CFM you want. For example, if you have a room that is 500 square feet with 8 foot ceilings, your equation would be:

500(square foot room) x 8(foot ceiling height) = 4000 ÷ 2 = 2000 CFM.

The average ceiling height is 8 feet so unless you have really high ceilings or an industrial space you can probably assume 8 feet. To get the square footage of your room just take the length x the width, so a 20 foot by 15 foot room would be 20 x 15 = 300 square feet, take that number x 8 foot ceilings is 300 x 8 = 2400 cubic feet, divide that number by 2 or cut that number in half so you would want at least a 1200 CFM Swamp Cooler for a room this size. It’s simple unless you don’t like math, in that case a calculator will work wonders, calculators love math.

Length x width of room = square feet x ceiling height ÷ 2 = CFM.

If you are getting a portable cooler that you will move from room to room it is best to calculate the size of the largest room you will want to cool, and you can’t go wrong if you get an evaporative cooler with a greater capacity than the room requires, that is better than getting a cooler that under performs in a room you want to cool.

The formula for calculating evaporative cooler sizing for outdoor use is as follows:

It is difficult to calculate the evaporative cooler CFM sizing for outdoor use since there is no ceiling and generally no set room size so no cubic feet calculations. How high is the sky? Even a calculator has a hard time answering that, so we will have to skip that step. Determining the proper evaporative cooler sizing for your outdoor needs is generally get the highest CFM cooler you can afford. You are not cooling down a room that retains the cool air, you are relying on the cooler to blow cool air in your direction.

Most outdoor Swamp Coolers will indicate an outdoor coverage area in square feet, which will help give you a general idea of how far the fan will blow the cool air. On average an outdoor cooler will cool about 1/4 to 1/3 of the CFM rating, For example, a 2000 CFM swamp cooler will cover about 500 to 650 square feet, while a 10,000 CFM unit can cool an area of 2500 to 3300 square feet, this can vary so check the specs when shopping for an outdoor cooler. A large blowing fan with a low power motor is generally more effective than a smaller blowing fan with a high power motor for outdoor use. Other things to consider when getting a cooler for the great outdoors is water tank size, the larger the water tank the less you have to fill it, another good option is a cooler with a hose hook up if you have access to a hose.

Other considerations for Swamp Cooler sizing and efficiency in addition to the CFM rating is climate and humidity. Since evaporative cooling relies on the process of evaporating water to cool the air, they work best in arid, hot, dry climates. If the air is too humid it already contains lots of moisture so a swamp cooler will not be as effective.

Below is a chart that shows the optimum temperature and humidity conditions for Evaporative Coolers. You can see at 110°F and 2% relative humidity an Evaporative Cooler can cool the air to 35°F cooler, at 90°F and 75% humidity it only cools the air to 4°F cooler.

So is a Swamp Cooler right for you? If you live in a dry climate the answer is probably YES. Swamp Coolers, aka Evaporative Coolers, cost a fraction of conventional compressor based air conditioning with comparable cooling capabilities. Swamp Coolers use much less energy than conventional air conditioners and they are environmentally friendly, so choosing a Swamp Cooler as your cooling solution can help save you money on electric bills and help keep the environment clean while keeping you and your family and friends cool and comfortable in hot dry climates.

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